通用小型汽油机进排气系统试验台设计与应用

针对国内通用小型汽油机生产中出现的问题,为提高汽油机进排气系统的流通能力和降低整机排放,设计了用于通用小型汽油机进排气系统的稳流试验台,对稳流试验台用于汽油机的研究、零部件检验和整机质量控制的功能做了介绍,以1P68F汽油机为例,对汽油机的进排气系统进行了初步稳流试验,对试验结果进行了分析,结果表明通用小型汽油机进排气系统零部件流动性能普遍较差。按内燃机流动特性进行优化设计、处理好压铸件工艺要求与流通性能的矛盾,改进通用小型汽油机进排气系统零部件质量,能提高我国通用小型汽油机的性能和产品技术水平。     

Findings from a fleet test on the performance of two engine oil formulations in automotive CNG engines

This work presents a comparative assessment of engine oil performance on field test using urban transport vehicles powered by compressed natural gas engines using two different mineral oil formulations approved by engine manufacturer. The first one is considered as a baseline reference, and the second one is a higher quality formulation in terms of base stock refining and additive content. Higher quality oil has shown a significant enhanced lubricant performance, leading to reach the oil drain interval defined by engine manufacturer on these engines without penalties in maintenance costs. In order to assess oil performance, an oil analysis programme has been established for oil samples collected from vehicles operated under real service conditions in an urban transport fleet. Monitored parameters include oxidation, nitration, aminic anti‐oxidant additives depletion, anti‐wear additives depletion, total acid number, total basic number and remaining useful life number (as an estimation of anti‐oxidant additive depletion including aminic and zinc dialkyldithiophosphate). Results obtained in more than 90 samples from 15 different vehicles have shown higher degradation rates for low quality lubricant oil formulation. This deviation can be explained taking into account factors related with lower anti‐oxidant additives content and lower thermal stability that can be mainly related with the base stock quality. This lower oil performance can be finally converted into higher vehicle maintenance cost and lower engine reliability. Copyright © 2013 John Wiley & Sons, Ltd.     

内燃机性能测试与测量不确定度

按JJF1059-1999《测量不确定度评定与表示》规定的程序和方法，对引起内燃机功率及燃油消耗率测量结果不确定度的因素及其效应进行不确定度分析与评定，旨在找出不确定度主要因素，采取适当措施，提高内燃机性能测量结果的质量，并促进推广测量不确定度评定工作的开展。     

New field and engine test data to demonstrate the wear protection benefits of a unique boundary chemistry (UBC)

The wear protection performance of unique boundary chemistry (UBC), both while in the engine and after removal, was tested with reference to commercial API SG, API SH/ILSAC GF-1, and API SJ/ILSAC GF-2 quality oils in two 80,450 km field tests, in modified and standard sequence tests, and in radiotracer engine studies. The radiotracer tests of UBC added to an API SJ/ILSAC GF-2 quality oil replicated previously published results of wear reductions achieved in a comparison of an API SH/ILSAC GF-1 oil with and without UBC. In extended Sequence IIIE runs, two engines, each lubricated with the same API SH/ILSAC GF-1 oil, were unable to complete the tests as a result of excessive oil consumption due to hot stuck rings. In contrast, two Sequence IIIE engines lubricated with the same API SH/ILSAC GF-1 oil treated with UBC completed the extended test without incident, even though the UBC-treated API SH/ILSAC GF-1 oil replaced the API SH/ILSAC GF-1 oil for the first oil drain interval only. A fully formulated SAE 5W–30 oil, which contained a full complement of UBC (20%), met all the requirements of API SH/ILSAC GF-1 quality and gave very low average and maximum cam and cam plus lifter wear on standard ASTM Sequence VE and IIIE tests. The same API SH/ILSAC GF-1 oil without UBC gave somewhat higher wear on both tests, but both oils met API SH/ILSAC GF-1 requirements. Wear metals analysis of a field test of 36 taxicabs, which compared an API SJ/ILSAC GF-2 quality oil to the same oil treated with UBC for the first drain interval, and also to a UBC-treated oil at every oil change, showed a reduction in the rate of used oil Fe accumulation for both methods of UBC treatment. This test also revealed a striking impact on Fe levels from Si found in used oil samples during an episode of Si contamination in local gasoline supplies. Finally, in a field test of 10 taxicabs, with parts measured before and after testing, wear reductions were observed in rings and bearings in UBC-treated cabs compared to those with API SG oil alone.     

涡喷发动机动态模拟试验台测控系统设计

针对涡喷6、7和涡喷13发动机主、加力燃油调节器的动态模拟试验台，设计了试验台测控系统。介绍了系统的组成、硬件设计、软件设计和系统的应用。测试结果表明，该系统具有测试精度高、可靠性好、操作和维护方便等特点，可用于涡喷发动机的科研和教学。     

Improvement of the acceptance test procedure for the external combustion engine after assembly by using the relationship between diagnostic parameters

A method to modernize the acceptance test procedure of external combustion engines by using the relationship between structural and diagnostic parameters is suggested. The idea for modernization is as follows: to use the transient modes for testing instead of stationary ones.     

A screening test for anti-wear additives in a modified four-ball test

Modern engine tests that evaluate the anti-wear properties of automotive engine oils are increasingly sophisticated and expensive, and often have relatively poor precision. The development of a simple, inexpensive, and reliable bench test to screen the anti-wear properties of fully formulated engine oils prior to their testing in engines is therefore very attractive. Numerous methods already exist, but they typically measure wear only at the end of the test by measuring the consequences of wear. The present paper describes an alternative approach, its purpose being the comparative evaluation of the anti-wear performance of lubricants throughout the test under variable load. A four-ball machine was used as a test rig for this work, and was equipped with instruments allowing study of the oil bath temperature, load applied to the balls, and the displacement of the load lever arm. The work presented focuses on a test procedure containing the following important elements: pre-ageing of oils, test start-up at very low load, incremental increases in load, stepwise increase in load, with each step sufficiently long to allow system equilibrium. Recording and analysis of the temperature and arm displacement curves permit the recognition of two distinct forms of wear: slow and gradual abrasive wear, and sudden and intense adhesive wear (scuffing). The presence and the intensity of the latter were found to have a direct relation with the anti-wear performance of candidate oils in the API Sequence VE engine test. The procedure ranked oils correctly in relation to their dithiophosphate concentration, correctly distinguished secondary and primary zinc dithiophosphates and, more interestingly, predicted the positive effects of some ashless anti-wear additives in accordance with results obtained in the Sequence VE.     

Real-time analysis system for gas turbine ground test acoustic measurements

This paper provides an overview of a data system upgrade to the Pratt and Whitney facility designed for making acoustic measurements on aircraft gas turbine engines. A data system upgrade was undertaken because the return-on-investment was determined to be extremely high. That is, the savings on the first test series recovered the cost of the hardware. The commercial system selected for this application utilizes 48 input channels, which allows either 1/3 octave and/or narrow-band analyses to be preformed real-time. A high-speed disk drive allows raw data from all 48 channels to be stored simultaneously while the analyses are being preformed. Results of tests to ensure compliance of the new system with regulations and with existing systems are presented. Test times were reduced from 5 h to 1 h of engine run time per engine configuration by the introduction of this new system. Conservative cost reduction estimates for future acoustic testing are 75% on items related to engine run time and 50% on items related to the overall length of the test.     

Modeling and fuzzy control of the engine coolant conditioning system in an IC engine test bed

Mechanical and thermodynamical performance of internal combustion engines is significantly affected by the engine working temperature. In an engine test bed, the internal combustion engines are tested in different operating conditions using a dynamometer. It is required that the engine temperature be controlled precisely, particularly in transient states. This precise control can be achieved by an engine coolant conditioning system mainly consisting of a heat exchanger, a control valve, and a controller. In this study, constitutive equations of the system are derived first. These differential equations show the second-order nonlinear time-varying dynamics of the system. The model is validated with the experimental data providing satisfactory results. After presenting the dynamic equations of the system, a fuzzy controller is designed based on our prior knowledge of the system. The fuzzy rules and the membership functions are derived by a trial and error and heuristic method. Because of the nonlinear nature of the system the fuzzy rules are set to satisfy the requirements of the temperature control for different operating conditions of the engine. The performance of the fuzzy controller is compared with a PI one for different transient conditions. The results of the simulation show the better performance of the fuzzy controller. The main advantages of the fuzzy controller are the shorter settling time, smaller overshoot, and improved performance especially in the transient states of the system.     

Design and calibration test of a support force measuring system for hypersonic vehicle aerodynamic measurement

With the development of air-breathing integrated vehicle test models equipped with engines, the designing of traditional internal balance force measuring systems has become complicated. This is partly because hypersonic vehicle models have slender bodies, and engine systems inside such model cavities are densely distributed, thereby limiting the space available to house traditional internal balance systems. Moreover, traditional force measuring systems are assembled mechanical systems, and their dynamic force transmission characteristics are inevitably degraded under extremely short test time conditions. Thus, herein, we propose a support force measuring system that integrates the traditional internal balance system with a support in an integral design. The designed internal triangular concurrent force system considerably reduces the additional moment generated by the thrust/resistance force. Calibration tests reveal that the new system demonstrates good linearity and repeatability, and the results prove the correctness of the triangular concurrent force system structure principle.     

操作机主工作缸压力试验

压力试验是大型压力缸制造的最终环节,是对压力缸制造质量的综合检验,掌握正确的压力试验要领,是成功的关键。     

Component transfer path analysis method with compensation for test bench dynamics

In this article a component transfer path analysis (TPA) procedure is proposed. The method allows one to calculate the total system response resulting from a subcomponent's source excitation. It is based on the knowledge of the frequency response functions (FRFs) of the total system and on a measurement of the stand-alone subcomponent on a test bench. As the true source excitation, for example an engines combustion, is not measurable, equivalent forces at the subcomponent interface are found. The equivalent forces are multiplied with the total system FRFs from the subcomponent interface to response nodes of interest. The resulting responses at and in front of the subcomponent interface are shown to be physically exact for linear, time invariant and stationary operating systems.However, for the method to succeed, the source forces will have to be independent of the global dynamics. In addition, the test bench needs to be rigid in the frequency range of interest. This is typically hard to achieve for analysis in the mid frequency range (100–1000 Hz in vehicle acoustics). Therefore, a way to compensate for the test bench dynamics is also discussed. It is shown that one needs the receptance matrix of the free component at its interfaces and the operational motions of the interface on the test bench. Knowledge of the test bench dynamics is not needed.Measuring excitation and response at the source interface may not be feasible in practice due to space restrictions. In this case, the proposed TPA method can be extended with substitute nodes on the subsystem which are reachable on the test setup and the total system. With the knowledge of the free subcomponent FRFs, physically exact responses at and in front of the gearbox interface can also be calculated.     

发动机冷试关键技术的研究

发动机作为汽车的核心部件,其装配质量直接影响整车性能,在发动机生产线末端通常都安装有试验设备来对发动机装配质量进行检测。发动机冷试技术作为一种新型的发动机装配质量在线检测技术,具有测试时间短、精度高、成本低、污染少等优点,在国内被越来越多的汽车厂商引入到发动机装配线上。阐述了冷试的概念及故障映像原理,并详细对冷试中扭矩检测、机油压力检测、正时检测、点火检测、进气真空度检测及排气压力检测关键技术进行了研究。     

Hot-fire injector test for determination of combustion stability boundaries using model chamber

This study realizes the conceptual method to predict combustion instability in actual full-scale combustion chamber of rocket engines by experimental tests with model (sub-scale) chamber. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions, and hot-fire test procedures were followed to obtain stability boundaries. From the experimental tests, two instability regions are presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio, which are customary for combustor designers. It is found that instability characteristics in the chamber with the adopted jet injectors can be explained by the correlation between the characteristic burning or mixing time and the characteristic acoustic time. In each instability region, dynamic behaviors of flames are investigated to verify the hydrodynamically-derived characteristic lengths of the jet injectors. Large-amplitude pressure oscillation observed in upper instability region is found to be generated by lifted-off flames.     

Optimization algorithm for diesel engine operating parameters based on a vehicle driving test cycle

For compliance with stringent exhaust emissions regulations, diesel engines have been equipped with electronically controlled components. Hence, there are various engine operating parameters that must be optimized, however optimization of these parameters is complicated. The objective of this research is to provide a new optimization algorithm for the diesel engine operating parameters with consideration of the vehicle control strategy. To optimize engine operating parameters, the concept of the vehicle-based optimization has been introduced. The engine response functions for performance and emissions were determined using the design of experiments, the response surface method and regression method with various engine operating parameters. Then, the engine operating points of the vehicle during the test cycles were analyzed, and the fuel consumption and emissions were estimated. Consequently, the engine operating parameters at each operating point were optimized to reduce the fuel consumption and the emissions such as NOx and PM by using the gradient method. Moreover, a new optimization algorithm enables to optimize engine operating parameters in various test cycle without additional engine experiment.     

Acoustical signature analysis of a helicopter cabin in steady-state and run up operational conditions

The noise situation inside modern helicopter cabins is still unsatisfying in comparison to modern jet. The requirement of a quieter helicopter needs a systematic study of its Noise Vibration and Harshness (NVH) behaviour. In this context, the authors have performed a wide experimental vibro-acoustic campaign in a helicopter cabin, which aims at evaluating the importance of the noise contribution produced by the jet engines with respect to the gearbox as well as finding possible noise sources and leakage points on the cabin surface. The results show that the main noise and vibration sources are the jet engines and the gearbox. Furthermore, the contribution of the jet engines is dominant with respect to the contribution of the gearbox, in terms of sound quality parameters. Finally, the paper suggests a fast and efficient experimental tool for leakage point detection and relative quantification on the cabin, very useful for noise control and quality check.     

加工中心主轴温升实验装置的设计

为了检验主轴的制造和装配质量,利用实验装置模拟主轴实际工作状况进行温升测试,把温升数据采集下来输入计算机进行数据分析,绘制出主轴温升曲线图或图表,通过技术分析判定主轴的整体质量。     

Behaviour of synthetic oils in aero engines

Within the framework of the high safety requirement imposed on aero engines, it is understandable that the oil for these engines should also be subject to high quality requirements. These have risen over the years alongside engine performances up to supersonic flight, where mineral oils could no longer meet the demands imposed by such high-performance engines. They have been superseded by synthetic ester oils, especially because of their more suitable viscosity-temperature behaviour. This paper deals with the behaviour of these synthetic oils in aero engines and concentrates on the thermo-oxidative strength and the effects on the engine oil and the engine itself.     

Laboratory evaluation of the dispersancy power of a gasoline engine oil and its relationship with sequence VE test results

The evaluation of the dispersancy power of a gasoline engine oil is included among such international specifications as those of the Committee of Common Market Automobile Constructors (CCMC) and the American Petroleum Institute (API). Such an evaluation is carried out by means of long, severe, and expensive engine bench tests, the engines used being Mercedes M102E (CCMC G4 and G5 levels) or the Ford Pinto 2.3 (API SG and SH levels). The cost of these tests necessitates pre-selection of oils by laboratory tests and these need to be a reliable indicator of bench test performance. The present study proposes two new laboratory methods, the OXYDISP and the POTDISP tests, which associate artificial ageing of the lubricants with modified blotter spots tests. These tests showed excellent correlation with Sequence VE engine test results. They were also capable of distinguishing oils of different API standards. They therefore provide an effective tool for preselection of lubricants, without pretending to be a replacement of or substitute for Sequence VE or other engine bench tests.